/*
 * Copyright 2013-2018 Lilinfeng.
 *  
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *  
 *      http://www.apache.org/licenses/LICENSE-2.0
 *  
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package com.phei.netty.protocol.websocket.server;

import static io.netty.handler.codec.http.HttpHeaders.isKeepAlive;
import static io.netty.handler.codec.http.HttpHeaders.setContentLength;
import static io.netty.handler.codec.http.HttpResponseStatus.BAD_REQUEST;
import static io.netty.handler.codec.http.HttpVersion.HTTP_1_1;
import io.netty.buffer.ByteBuf;
import io.netty.buffer.Unpooled;
import io.netty.channel.ChannelFuture;
import io.netty.channel.ChannelFutureListener;
import io.netty.channel.ChannelHandlerContext;
import io.netty.channel.SimpleChannelInboundHandler;
import io.netty.handler.codec.http.DefaultFullHttpResponse;
import io.netty.handler.codec.http.FullHttpRequest;
import io.netty.handler.codec.http.FullHttpResponse;
import io.netty.handler.codec.http.websocketx.CloseWebSocketFrame;
import io.netty.handler.codec.http.websocketx.PingWebSocketFrame;
import io.netty.handler.codec.http.websocketx.PongWebSocketFrame;
import io.netty.handler.codec.http.websocketx.TextWebSocketFrame;
import io.netty.handler.codec.http.websocketx.WebSocketFrame;
import io.netty.handler.codec.http.websocketx.WebSocketServerHandshaker;
import io.netty.handler.codec.http.websocketx.WebSocketServerHandshakerFactory;
import io.netty.util.CharsetUtil;

import java.util.logging.Level;
import java.util.logging.Logger;

/**
 * @author lilinfeng
 * @date 2014年2月14日
 * @version 1.0
 */
public class WebSocketServerHandler extends SimpleChannelInboundHandler<Object> {
	
	private static final Logger logger = Logger.getLogger(WebSocketServerHandler.class.getName());

	private WebSocketServerHandshaker handshaker;

	@Override
	public void messageReceived(ChannelHandlerContext ctx, Object msg) throws Exception {
		// 传统的HTTP接入，第一次握手由HTTP协议承载
		if (msg instanceof FullHttpRequest) {
			handleHttpRequest(ctx, (FullHttpRequest) msg);
		} else if (msg instanceof WebSocketFrame) { 
			// WebSocket接入
			handleWebSocketFrame(ctx, (WebSocketFrame) msg);
		}
	}

	@Override
	public void channelReadComplete(ChannelHandlerContext ctx) throws Exception {
		ctx.flush();
	}

	private void handleHttpRequest(ChannelHandlerContext ctx, FullHttpRequest req) throws Exception {

		// 如果HTTP解码失败，返回HHTP异常
		if (!req.getDecoderResult().isSuccess() || (!"websocket".equals(req.headers().get("Upgrade")))) {
			sendHttpResponse(ctx, req, new DefaultFullHttpResponse(HTTP_1_1, BAD_REQUEST));
			return;
		}

		// 构造握手响应返回，本机测试
		System.out.println("构造握手响应返回 ... ");
		WebSocketServerHandshakerFactory wsFactory = new WebSocketServerHandshakerFactory(
				"ws://localhost:8080/websocket", null, false);
		handshaker = wsFactory.newHandshaker(req);
		if (handshaker == null) {
			WebSocketServerHandshakerFactory.sendUnsupportedWebSocketVersionResponse(ctx.channel());
		} else {
			handshaker.handshake(ctx.channel(), req);
		}
	}

	private void handleWebSocketFrame(ChannelHandlerContext ctx, WebSocketFrame frame) {
		System.out.println("webSocket message ... ");
		// 判断是否是关闭链路的指令
		if (frame instanceof CloseWebSocketFrame) {
			handshaker.close(ctx.channel(), (CloseWebSocketFrame) frame.retain());
			return;
		}
		// 判断是否是Ping消息
		if (frame instanceof PingWebSocketFrame) {
			ctx.channel().write(new PongWebSocketFrame(frame.content().retain()));
			return;
		}
		// 本例程仅支持文本消息，不支持二进制消息
		if (!(frame instanceof TextWebSocketFrame)) {
			throw new UnsupportedOperationException(
					String.format("%s frame types not supported", frame.getClass().getName()));
		}

		// 返回应答消息
		String request = ((TextWebSocketFrame) frame).text();
		if (logger.isLoggable(Level.FINE)) {
			logger.fine(String.format("%s received %s", ctx.channel(), request));
		}
		ctx.channel().write(
				new TextWebSocketFrame(request + " , 欢迎使用Netty WebSocket服务，现在时刻：" + new java.util.Date().toString()));
	}

	private static void sendHttpResponse(ChannelHandlerContext ctx, FullHttpRequest req, FullHttpResponse res) {
		// 返回应答给客户端
		if (res.getStatus().code() != 200) {
			ByteBuf buf = Unpooled.copiedBuffer(res.getStatus().toString(), CharsetUtil.UTF_8);
			res.content().writeBytes(buf);
			buf.release();
			setContentLength(res, res.content().readableBytes());
		}

		// 如果是非Keep-Alive，关闭连接
		ChannelFuture f = ctx.channel().writeAndFlush(res);
		if (!isKeepAlive(req) || res.getStatus().code() != 200) {
			f.addListener(ChannelFutureListener.CLOSE);
		}
	}

	@Override
	public void exceptionCaught(ChannelHandlerContext ctx, Throwable cause) throws Exception {
		cause.printStackTrace();
		ctx.close();
	}
}
